Condition monitoring of railway assets is used to determine what state the many assets belonging to the railway network are in, in order to schedule maintenance, detect potential faults or unusual operation. Systems are employed to monitor one or many aspects of an asset and based on the value(s) of the measures, an alarm may be raise to indicate a particular condition.
One example of a type of railway asset that is monitored is a points machine (also known as a switch)—an electromechanical system that allows trains to be guided from one track to another. The switch is operated by an electrical motor. Remote condition monitoring systems are used to measure electrical usage parameter(s) associated with the switch during its operation and compare the value(s) with threshold values; for example, a remote monitoring system may measure the average current of the electrical motor during its operation and compare the average current with a static threshold. If the average current is above the threshold then the system goes through the process of reporting this as unusual/undesirable, and a decision is made as to how to respond.
Conventional monitoring systems generate an unacceptably high number of false positive alarms that are attributed to changes in weather conditions; an estimated 11% of false alarms generated by rail asset remote conditioning systems are attributed to changes in environmental conditions, rather than being genuinely indicative of poor asset condition. The static thresholds currently used may also mean that in some cases, the asset may operate outside of acceptable tolerances, without an alert being issued.
Thus, it is desirable to provide enhanced means for recognising when a railway asset is operating within acceptable tolerances.